From the contaminated soils to the ecocatalysts: An original investigation

Abstract

COMInternational audienceThe number of contaminated sites by metals and metalloids (As, Cd, Cu, Pb and Zn) was around 1 250,000 in Europe in 2016. Most of them are located in France, notably in Northern France where numerous habitants live due to the high past industrial activities (mining, metallurgical, inorganic and organic chemistry). Consequently, environmental and sanitary problems like degradation and perturbation of soil activities (loss of the biodiversity…), non-compliant agricultural commodity, production of contaminated vegetables, lead poisoning and different types of symptoms in relation with metal human exposure were highlighted. This explains why the management of these contaminated soils (agricultural, urban and forest) is a great concern in the Hauts-de-France region and particularly in the contaminated area affected by the dust emission of two former lead and zinc smelters.Physical and chemical techniques (soil removal, soil washing, electrokinetic…) are widely used to remediate contaminated soils. However, most of them are expensive and destructive (fauna and flora are highly impacted and the resulting soils are often non-productive).To avoid the dispersion of contaminated soil particles, to restore contaminated sites and ecosystems and to maintain an economic activity in this area, an environmental friendly management based on the concept of assisted-phytoremediation and assisted-phytoextraction was studied. From this approach, the first interest was to immobilise the carcinogenic metals (Cd, Pb) and the second was to increase non-carcinogenic metal uptake by plants in order to elaborate new heterogeneous catalysts (called ecocatalysts) from the plant biomass. These bio-sourced catalysts were used in organic synthesis to produce pharmaceuticals taking into account the green chemistry concept. It was highlighted that these new catalysts were reusable, increased the reaction yields while minimizing the production of waste